This invention relates to a pluggable transceiver module for use in a fiber optic switch.
Fiber optics are increasingly used for transmitting data signals. Typically, when data is transmitted by an optical network, it must be converted from an electrical signal to a light signal, and visa versa. In order to effectuate the conversion between electrical and optical signals, a transceiver module is used at both ends of a fiber optic cable. Each transceiver module typically contains a laser transmitter circuit capable of converting electrical signals to optical signals, and an optical receiver capable of converting received optical signals back into electrical signals.
Typically, a transceiver module is electrically interfaced with a host device, such as a host computer, switching hub, network router, switch box, computer I/O or the like. In many applications is it desirable for the transceiver modules to be “hot-pluggable,” that is, the transceiver module may be inserted into and removed from the host system without removing electrical power. In this way, if a transceiver module fails, it can more readily be removed from the host device and replaced with a new module without soldering or the like.
Consequently, several pluggable transceiver module designs and standards have been introduced in which a pluggable transceiver module plugs into a receptacle which is electronically connected to a host circuit board. For example, such a standard is delineated in the Small Form-Factor Pluggable (SFP) Transceiver Multi-Source Agreement (MSA), dated Sep. 14, 2000. Such standards define a receptacle or cage that receives a transceiver module. The cage includes a cage latch. The transceiver module includes a latch boss which fits into the cage latch. The transceiver module also includes an actuator configured to engage the cage latch and deflect the cage latch away from the latch boss, thereby releasing the transceiver module from the cage. An exposed feature of the transceiver module is color coded to indicate if the transceiver module is multi-mode or single mode.
Typically, fiber optic components use color to designate mode (e.g., wavelength, contact type, product type, etc.), or in specific applications to designate user-specific information. Transceiver modules are generally small, with only a small portion of transceiver module visible when installed. The transceiver modules are also often installed in hard to access areas. It is difficult, therefore, to ensure that the mode designation color is visible to the user. Previously, color designation has been accomplished by, for example, manufacturing the entire assembly out of a single color material (typically a plastic), manufacturing the entire front of the module out of a single color material, or providing colored handles. However, manufacturing an entire assembly or significant portion thereof out of a single color material limits the usefulness of the assembly, as components of a particular color can only be used with a particular mode. In addition, to provide the necessary strength and visibility, plastic components are typically larger than would be preferred and add unwanted size to the device. Also, for some applications it is desirable to form components from materials which is not easily colored (such as metal for EMI shielding). Finally, although various standards have been given for the configuration of the transceiver module and the cage, variations between manufacturers exist as to some of the specific configurations. The variations between manufacturers are sometimes intended to satisfy different end-user requirements, such as how the transceiver is extracted from the cage. Consequently, some configurations of transceiver modules do not utilize components such as handles, making a color designating handle feature of no advantage. It is therefore desirable to have a color mode indicator that does not add to the size of the transceiver module, and that is easily adaptable and usable with different configurations of modules without requiring different tooling, molds, components, etc.